Refine contribution #4083

Add "Spring Batch Architecture" section to the index

Author: fmbenhassine

spring-batch-docs/src/main/asciidoc/index.adoc

@@ -11,6 +11,8 @@ The reference documentation is divided into several sections:
 [horizontal]
 <<spring-batch-intro.adoc#spring-batch-intro,Spring Batch Introduction>> :: Background, usage
  scenarios, and general guidelines.
+<<spring-batch-architecture.adoc#springBatchArchitecture,Spring Batch Architecture>> :: Spring Batch
+architecture, general batch principles, batch processing strategies.
 <<whatsnew.adoc#whatsNew,What's new in Spring Batch 5.0>> :: New features introduced in version 5.0.
 <<domain.adoc#domainLanguageOfBatch,The Domain Language of Batch>> :: Core concepts and abstractions
 of the Batch domain language.

spring-batch-docs/src/main/asciidoc/spring-batch-architecture.adoc

@@ -1,6 +1,6 @@
 [[springBatchArchitecture]]
 === Spring Batch Architecture
-// TODO Make a separate document
+
 Spring Batch is designed with extensibility and a diverse group of end users in mind. The
 following image shows the layered architecture that supports the extensibility and ease of
 use for end-user developers.